The artist seems to be inspired by Ivan Aivazovsky.

https://www.wikiart.org/en/ivan-aivazovsky

Notably: Storm on the North Sea

https://arthive.com/ivanaivazovsky/works/35183~Storm_on_the_North_sea

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Can't directly explain the windmill, but in the Norse, salt is churned into ocean with a mill --- but a different sort of mill...

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http://www.orkneyjar.com/folklore/pentland.htm

http://www.germanicmythology.com/original/cosmology5.html